The present invention relates to a technique for emphasizing or depressing a prosody (e.g., modulation of a volume, pitch, etc.) of voice.
Heretofore, there have been proposed techniques for varying a prosody of voice. Japanese Patent Application Laid-open Publication No. 2004-252085, for example, discloses a technique for depressing a prosody by decreasing variation widths of a volume and pitch of a voice signal to predetermined ranges (hereinafter referred to as “reference ranges”). The reference ranges are fixedly set in accordance with standard variation widths of volumes and pitches of voice uttered or generated in a calm state.
However, with the technique disclosed in the No. 2004-252085 publication, where the fixedly-set reference ranges are used to depress a volume and pitch irrespective of characters of a voice signal to be actually processed, it is difficult to perform appropriate voice prosody control corresponding to the characters of the voice signal. For example, if the volume and pitch of a voice signal to be processed fall within the reference ranges, there would occur no change in prosody between before and after the processing.